Entity framework: cross join causes OutOfMemoryException - entity-framework

Question

I've got a table with 1.5 million records on a SQL Server 2008. There's a varchar column 'ReferenzNummer' that is indexed.
The following query executed in the SQL Management Studio works and is fast:
SELECT v1.Id, v2.Id FROM Vorpapier as v1 cross join Vorpapier as v2
WHERE v1.ReferenzNummer LIKE '7bd48e26-58d9-4c31-a755-a15500bce4c4'
AND v2.ReferenzNummer LIKE '7bd4%'
(I know the query does not make much sense like this, there will be more constraints, but that's not important for the moment)
Now I'd like to execute a query like this from Entity Framework 5.0, my LINQ looks like this:
var result = (from v1 in vorpapierRepository.DbSet
from v2 in vorpapierRepository.DbSet
where v1.ReferenzNummer == "7bd48e26-58d9-4c31-a755-a15500bce4c4" &&
v2.ReferenzNummer.StartsWith("7bd4")
select new { V1 = v1.Id, V2 = v2.Id })
.Take(10)
.ToList();
This tries to load the whole table into memory, leading to an OutOfMemoryException after some time. I've tried to move the WHERE parts, with no success:
var result = (from v1 in vorpapierRepository.DbSet.Where(v => v.ReferenzNummer == "7bd48e26-58d9-4c31-a755-a15500bce4c4")
from v2 in vorpapierRepository.DbSet.Where(v => v.ReferenzNummer.StartsWith("7bd4"))
select new { V1 = v1.Id, V2 = v2.Id })
.Take(10)
.ToList();
Is it possible to tell Entity Framework to create a cross join statement, like the one I've written myself?
UPDATE 1
The EF generated SQL looks like this (for both queries)
SELECT [Extent1].[Id] AS [Id],
[Extent1].[VorpapierArtId] AS [VorpapierArtId],
[Extent1].[ReferenzNummer] AS [ReferenzNummer],
[Extent1].[IsImported] AS [IsImported],
[Extent1].[DwhVorpapierId] AS [DwhVorpapierId],
[Extent1].[Datenbasis_Id] AS [Datenbasis_Id]
FROM [dbo].[Vorpapier] AS [Extent1]
UPDATE 2
When I change the LINQ query and join the table with itself on the field DatenbasisIDd (which is not exactly what I want, but it might work), EF creates a join:
var result = (from v1 in vorpapierRepository.DbSet
join v2 in vorpapierRepository.DbSet
on v1.DatenbasisId equals v2.DatenbasisId
where v1.ReferenzNummer == "7bd48e26-58d9-4c31-a755-a15500bce4c4" && v2.ReferenzNummer.StartsWith("7bd4")
select new { V1 = v1.Id, V2 = v2.Id })
.Take(10)
.ToList();
The resulting SQL query looks like this. It works and is fast enough.
SELECT TOP (10) 1 AS [C1],
[Extent1].[Id] AS [Id],
[Extent2].[Id] AS [Id1]
FROM [dbo].[Vorpapier] AS [Extent1]
INNER JOIN [dbo].[Vorpapier] AS [Extent2]
ON ([Extent1].[Datenbasis_Id] = [Extent2].[Datenbasis_Id])
OR (([Extent1].[Datenbasis_Id] IS NULL)
AND ([Extent2].[Datenbasis_Id] IS NULL))
WHERE (N'7bd48e26-58d9-4c31-a755-a15500bce4c4' = [Extent1].[ReferenzNummer])
AND ([Extent2].[ReferenzNummer] LIKE N'7bd4%')
I still don't see, why EF doesn't create the cross join in the original query. Is it simply not supported?

Answer 1

If you use a join in the linq statement it will get passed back to SQL Server. Here are some examples of the join operator in linq: http://code.msdn.microsoft.com/LINQ-Join-Operators-dabef4e9